Water heaters are commonly employed in homes and small businesses to heat water for domestic use. Water heaters are produced in large numbers and sold to consumers in a very competitive market. A large portion of these devices use gaseous fuel, such as natural gas or bottled gas, as an energy source.
Conventional gas fired water heaters often include a tank adapted to contain a body of water, a water inlet, a water outlet, a combustion chamber disposed below or within the tank, a gas regulator and a burner disposed within the combustion chamber. The entire structure is thermally insulated. Conventionally, the gas regulator senses the temperature of water within the tank. When the water temperature drops below a certain minimum, gas is allowed to flow to the burner within the combustion chamber where it is ignited, heating the combustion chamber and the body of water above or around the combustion chamber. The products of combustion are vented through a flue connected to the combustion chamber and passing through the water containing tank. This general construction has been common for many years. Numerous variations upon this construction have been created in attempts to increase efficiency and otherwise improve operating characteristics.
Over the last several years, the efficiency of water heaters, especially fuel efficiency, has become an important characteristic. This is the result of government regulation and also heightened consumer awareness concerning consumption of natural resources. Over recent years, insulation technology has improved insulation characteristics of water heaters. However, production line burner technology has remained comparatively stagnant and, therefore, inefficient. Additionally, concern for the environment has made the elimination of potentially polluting substances from the products of combustion more important. While gas fired water heaters are very low polluters when compared to other fuel consuming products, there are many water heaters. Government bodies and consumers have therefore sought to further reduce the contribution of pollutants emanating from water heaters.
In addition to all of the above very important design criteria, cost is a very important factor in producing water heaters. Water heaters are purchased by builders and home owners in a very competitive environment. The products are mass produced and sold throughout a large marketplace. In the United States, national companies compete very aggressively for sales. Water heaters must therefore be very economically manufactured or they will not sell and consumers will not gain the benefits of design improvements.
In conventional water heaters, the above objects are not optimally achieved. Additionally, the cost of manufacturing remains high. A number of different components including a tank, a combustion chamber, a burner, a reflecting pan under the burner to protect the bottom of the water heater from burner heat and numerous other elements and insulation are manufactured and assembled. Often, changing a design to address one of the above identified problems compromises another of the problems or increases cost significantly.
An object of the invention is to provide a water heater of improved operating characteristics which is inexpensive to manufacture on a production basis.
It is another object of the present invention to provide a water heater which has reduced emissions of oxides of nitrogen.
It is still another object of the present invention to provide a water heater of improved fuel efficiency and having low standby heat loss.
It is yet another object of the present invention to provide a water heater which consumes less materials in production and is less expensive to manufacture.
It is still another object of the present invention to provide a water heater having cooler external surfaces around the combustion chamber whereby special insulation techniques are not required and which economically extracts the maximum amount of heat from flue gasses.
Further objects and advantages to the invention will appear from the following detailed description of a preferred embodiment thereof and from the accompanying drawings.
The present invention contemplates a new and improved water heater construction which overcomes the above referred to problems and others and provides a water heater of simpler construction which is economical to manufacture, economical to operate, burns fuel cleanly and answers governmental regulations.
Briefly stated, in accordance with one aspect of the invention, a water heater is provided having a tank adapted to contain a body of water and an integrated combustion chamber and ceramic burner assembly below the tank.
Still further in accordance with the invention, a skirt generally matching the cross section of the tank is positioned below the tank and gas tightly fixed to the tank. A burner shelf is positioned within this skirt and gas tightly fixed to the skirt around its entire periphery. A ceramic burner is positioned on the burner shelf separating the volume within the skirt into a combustion chamber above the burner shelf and a burner volume below the burner shelf. A bottom pan is gas tightly sealed to the skirt around its bottom forming a gas tight burner chamber below the burner shelf. An air and gas proportioner communicates through the skirt and into the burner chamber in a gas tight manner.